Automatic playing device for stringed instruments.



B. L. CARTMELL.

AUTOMATIC PLAYING DEVICE FOR STRINGED INSTRUMENTS.

APPLICATION FILED APR-'23. I915.

1,238,884. Patented Sept. 4,1917.

3 SHEETSSHEET I.

III IIIIIIIII.

Il' I/I/h ammo o B, L. CARTIVIELI...

AUTOMATIC PLAYING DEVICE FOR STRINGED INSTRUMENTS.

APPLICATION FILED APR- 23| IBIS.

1,288,884. Patented Sept. 4,1917.

3 SHEETSSHEET 2.

II I I w r :EZZ. w /00 /3 B. L. CARTMELL.

AUTOMATIC PLAYING DEVICE FOR STRINGED INSTRUMENTS.

APPLICATION FILEDIAPR. 23. 1915. 1,238,884. PatentedSept. 4, 1917.

3 SHEETS SHEET 3.

UNITED STATES PATENT OFFICE.

BENJAMIN L. CARTMELL, OF DAYTON, OHIO.

T 0 all whom it may concern:

Be it known that I, BENJAMIN L. CART- MELL, citizen of the UnitedStates, residing at Dayton, in the county of Montgomery and State ofOhio, have invented certain new and useful Improvements in .AutomaticPlaying Devices for Stringed Instruments, of which the following is aspecification.

My invention relates to automatic musical instruments and moreparticularly to an automatic playing apparatus applicable to stringedinstruments without necessitating any changes in the construction of theinstrument or involving any mutilation thereof.

The object of the invention is to simplify the structure as well as themeans and mode of operation of such apparatus whereby it will not onlybe cheapened in construction, but will be more efficient in use,positive in action, and unlikely to get out of repair.

A further object of the invention is to provide improved form of stringstopping devices and control means therefor and improved means foroperating the plectrums or picking devices. Y

A further object of the invention is to provide means for automaticallyvarying the intensity or modulating the sounds produced, therebyeffecting expression in the reproduction of the musical composition.

With the above primary and other incidental objects in view, as willmore fully appear in the specification, the invention consists of thefeatures of construction, the parts andvcombinations thereof, and themode of operation or their equivalents, as hereinafter described and setforth in the claims.

Referring to the drawings, Figure 1 is a front elevation of theassembled playing apparatus applied to a banjo. Fig. 2 is a sideelevation, partly in section, of the mechanism. Fig. 3 is an enlargeddetail view of the string stopping devices viewed from the side. Fig. lis an end elevation ofthe musical instrument illustrating the plectrumsand operating devices therefor. Fig. 5 is a trans verse sectional viewof the string stopping devices. Figs. 6 and 7 are detail plan view andvertical sectional view of the valve chest. Fig. 8 is a detailperspective view of the plectrum and its mounting. Fig. 9 is a detailperspective view of two of the string stopping devices. Figs. 10 and 11are diagrammatic views of the movement of the plectrum.

Like parts are indicated by similar char- Specification of LettersPatent.

AUTOMATIC PLAYING DEVICE FOR STRINGED INSTRUMENTS.

I Patented Sept. 4, 1917.

Application filed April 23, 1915. Serial No. 23,515.

acters of reference throughout the several VIEWS.

In the drawings there has been shown a complete playing mechanismadapted to be controlled by a perforated master or music sheet involvingnovel means for accomplish ing the winding and rewinding of the musicsheet and also improvements in the control valve for pneumaticallyoperated mechanisms of this character. For obvious reasons, however, thepresent invention is re stricted to those devices relating directly tothe manipulation of the stringed instrument, viz., the fingering,picking, and expression controlling devices. The remaining novelfeatures disclosed herein, including the con trol mechanism for windingand rewinding of the music sheet and the valve chest and other devicesare not abandoned, but, as at present advised, will form the subjectmatter of separate applications.

Referring to the drawings, 1 is the main frame or supporting structureupon the front board 2 of which there is detachably connected bysuitable clamping means a stringed instrument, which, in the presentinstance, is a banjo. It is obvious that other forms of instrument suchas a guitar, mandolin, zither, harp or other stringed instruments may besubstituted for the banjo shown in the drawings.

At its upper end the instrument rests upon a pillow block 3 secured tothe front board 2 to which the instrument is attached by a clampingplate 4 overlying the head of the instrument and attached to the pillowblock by clamping screws 5. At its lower end the instrument is securedto a bar 6 projecting from the front board 2 by means of clamps orclevises 7 engaging the head bar 8 of the banjo and a T shaped extension9 of the bar 6.. Located in the lower front portion of the frame 1 arethe wind and rewind rolls 10 and 11 upon which are carried from one tothe other the perforated music sheet 12. This perforated sheet 12 passesover a tracker bar 13 intermediate the rolls having therein a pluralityof orifices each connected by a conduit l i within the valve chest.

In the drawings, for convenience, two valve chests 15 and 16 have beenshown. In this particular construction the chest 15 pertains wholly tothe string stopping devices while thevalve chest 16 is connected withthe picking and modulating mechanism and also with various controldevices. It is obvious, however, that all the devices may be Q011-trolled from a single valve chest. chests 15 and 16 communicate througha conduit 17 with the actuating bellows or pump 18, the movable side ofwhich is connected by a pitman 20 with a crank arm 21. The crank shaft21 is rotated by a motor 22 or any other suitable driving device' In thepresent instance the motor 22 is connected by a belt 23 with a pulley 24upon the crank shaft. Associated with the bellows 18 is the usualequalizer 25.

The wind and rewind rolls 10 and 11 are driven by means of a belt 26from the pulley 27 on the crank shaft to a pulley 28 upon the countershaft 29 of the wind and rewind mechanism. The counter shaft 29 carriesa sprocket wheel 30 connected by a chain '31 with a corresponding"sprocket 32 upon the shaft of the. rewinding roll 11. The sprocket30,'however, is loose'upon the counter shaft 29 and is adapted to be engaged therewith by means of a sliding clutch member] 33 controlled by anoscillatory lever 34. 'Whenthelever 34 is reversed the sprocket30 isdisconnected from the shaft 29 and a gear pinion '35, carried by theclutch member 33, is caused to mesh with a. gear 36 upon the shaft ofthe winding roll 10. The operating mechanism thus far described is thatgenerally found in pneumatically operated mechanical playing apparatus.The control lever 34 is actuated to effect the windin-gand rewi-nding ofthe music sheet by means of a pneumatic or bellows 37 which is expandedby a spring 38 thereby causing the clutch member 33 to be engaged withthesprocket 30 whereby the rewinding roll 11 is driven from the countershaft 29. The pneumatic 37 is connected through the valve chest with themain bellows or pump 18 independent of the tracker bar. The constructionis such that the pneumatic 37 is collapsed whenever the main bellows '18is in effective operation. Upon the contraction of the pneumatic orbellows 37 under the influence of the main bellows or pump 18 the clutchmember 33 is shifted to effect the winding of the music sheet.

For convenience of manufacture the valve chests have been made up of aseries of layers or thicknesses of material, preferably wood, superposedone upon the other. Refer-ring to Figs. 6 and 7, these variousthicknesses or layers of material have been designated as a, b, c, d, e,and f. The lowermost portion a is provided with perforations or orifices40 with which the tubes or conduits 14 leading from the tracker barcommunicate. In the superposed thickness b there are provided aplurality of enlarged openings 41 forming chambers concentric with Thesethe orifices. 4Q. These openings or eham- 6 hers 41 are closed on theirupper side by a die hragm 42 of flexible material such as rub er,leather, fabric, or other material, forming an expansible side for thechamber which is commonly termed in the trade l as the pouch. Thesucceeding layer or thickness 0 comprises merely a marginal frameforming intermediate the layers or thicknesses b and d a suction orvacuum chamber 43 which is common to all the valve mechanisms in thechest. This suction chamber communicates with the main bellows or-pump18 through the conduit 17. The succeeding layer or thickness d, formingthe upper wall of common suction or vacuum chamber is provided with aplurality of orifices 44 communicating therewith. The thickness or layer0 superposed on the thickness d is provided with elongated openings 45re 1 istering with the orifices 44. Located -in the openings or chambers45 are valve heads 46 ,havin pendant stems 47 projectin through t eorifices 44 and resting at thei lower end upon the flexible diaphragm42. The top or cover of the chest is provided with two orifices leadingto the elongated chamber 45, the orifice 48 being a vent to theatmosphere adapted to be controlled by the valve 46', and the secondorifice 49 communi cates with the pneumatic control device. To preventthe displacement of the valve head 46 a stud or pin 50 is driven intothe portion (l beside the valve head 46. Leading from the main suctionor vacuum chamber 43 to the pouch 41 is a small duct 51 commonly knownas the bleed hole. This duct or bleed hole is controlled by a screw 52'by the adjustment of which it may be partially closed to regulate thepassage of w air therethrough and thereby control the rapidity ofaction. The construction is such that the air is exhausted from the mainsuction or vacuum chamber 43 by the operation of the pump or bellows 18thereby maintaining a partial vacuum therein which is extended throughthe bleed holes 51 to the pouches or chambers 41 which are therebymaintained in a state of partial vacuum. When a perforation of the musicsheet registers with a corresponding orifice of the tracker bar, air isadmitted through the orifice and the conduit 14 connected therewith tothe corresponding pouch or chamber 41. The inlet 40 being larger thanthe bleed hole 51, the air rushes into the chamber or pouch 41 at agreater rate than it can be withdrawn by the pump or bellows 18 actingthrough the common vacuum chamber 43. The result is that the dia-' phram or flexible side 42 of the pouch or cham er 41 is expanded upward byatmospheric pressure. Its movement, being transmitted through the stem47 of the valve 46 resting thereon, causes the valve 46 to be lifted toopen the orifice 44 and to close the vent 48. The orifice 44 beingopened and the vent closed, the influence of the suction bellows or pump18 is extended from the common suction or vacuum chamber 43 through theorifice 44, chamber 45, orifice 49 and conduit 53 connected therewith tothe pneumatic control device from which the air is exhausted, causingthe pneumatic to collapse and thereby perform its function. The mastersheet having continued to move across the tracker bar and theperforation having been moved from registry with the orifice of thetracker bar, thereby closing the latter, the continued action of themain bellows or pump 18 will exhaust the air from the chamber or pouch41, causing the flexible side or diaphragm 42 thereof to contract andpermitting the valve 46 to descend to close the orifice 44 and at thesame time open the vent 48. The opening of the 'vent 48'permits theentrance of air through the vent 48, the chamber and the connectingconduit 53 to the operated pneumatic which is expanded to normal by itsusual spring. For convenience in tracing the parts the conduitsconnecting the valve chest with the several sets of pneumatics have beensep'arably identified. The conduits leading to the fingering or stoppingde vices'have been designated as 53 the conduits leading to themodulating or expression control mechanisms are designated as 53", andthose controlling the Wind and rewind of the music sheet are designatedas 53 and 53 respectively.

In the drawings the banjo has been shown provided with but four strings,the fifth or thumb string having been omitted. The stringstoppingdevices are arranged as follows: Located on the front board 2 onopposite sides of the neck of the instrument are two boxes or housings54 and 55. Located in each of these housings are a plurality ofpneumatics or small bellows which, for convenience, are arranged in twoseries, one above the other. Hinged to the outer walls of the boxes orhousings 54 and 55 and pro jecting inward therefrom are parallel pivotedarms 56 preferably arranged in pairs. Each arm 56 is connected by asuitable link -with a. corresponding pneumatic or bellows 57. i Ithasbeen found in practice that the preferable form of connecting linkcomprises a string or cord 58 attached at 59 to the movable side of thepneumatic or bel lows and extending upward to and attached to the hingedor pivoted arm 56. The end of the pivoted arm 56 is preferably providedwith a diagonally disposed hole or orifice 60 through which theconnecting cord 58 is threaded and the end of the cord is securedbybeing wrapped arounl a con veniently located screw 61. However, in lieuof the diagonal perforation. the end of the arm may be provided with astaple or eye 62, as shown at the left in Fig. 9.

Held by each of the swinging or pivoted arms is a thin blade-likeextension 63 having a laterally projecting foot 64 overlying thecorresponding string of the instrument. The bladelike extensions 63 ofthe swinging arms are located on adjacent sides of the arms whereby theywill lie closely :uljacent one to the other with their laterallyextended feet 64 alined. adjacent to the corresponding fret of theinstrument neck. The inner walls of the housings 54 and 55 are slottedto form guides for the stopping devices, through which slots theextensions 63 extend. As shown in the drawings, the swinging arms of therespective boxes or housings 54 and 55 are alined one with the other sothat the extensions of the arms from one box or housing engage the twostrings to the right and those from the box to the left engage the twostrings to the left. The extensions 63'of the arms pertaining to themedial strings are recessed or notched as shown at 67 whereby whendepressed they will not interfere with the outermost strings. Theadjustment of the stopping arms or fingers is readily accomplished bythe loosening or tightening of the strings or cords 58. The feet orengaging portions 64 are covered on their under surface with leather,rubber or other suitable material which will prevent the abrasion of thestrings and also obviate any chatter or noise as the strings are pressedinto engagement with the neck. The music sheet is provided with one setof perforations, as at 65, which pertain to the pneumatics controllingthe fingering or string stopping devices and another set ofperforations'66 which pertain to the pneumatics controlling the pickingapparatus or plectrums.

Located on opposite sides of the body of the instrument are pneumaticsor bellows 69 controlling the operation of the picking devices orplectrums, one for each string and plectrum. In the present instancethese pneumatics have been arranged in pairs. The pneumatics carry attheir upper ends a frame or head 70 supported on the stationary side ofthe pneumatic from which extend inwardly disposed arms 71. Set screws 72in the frames or heads 70 serve to limit the movement of the flexiblesides of the pneumatics and thereby form the means of adj usting thedegree of movement of the plectrum. Secured to the opposite sides of theinstrument body by means of cross heads 73 engaging beneath the nuts ofthe head clamps are studs 74 which .engage the inward projecting arms 71and serve to support the body of the instrument rigidly in relation withthe frame and operating mechanism. The studs 7 4 extend above the arms71 and support a transverse bar 7 5 which may be adjusted vertically toand from the head of the instrument by the adjustment of the nuts 76 and77 upon the studs 74 to vary the relation of the plectrums with thestrings. The pickers or plectrums 78 are carried upon bell cranks 79both slidingly and pivotally mounted upon the cross bar 7 5. Each bellcrank 79 is provided with a slot 80 through which projects a stud orscrew 81 which forms the pivotal connection of the bell crank during itsoscillatory movement and a guide for its sliding movement. Bearing uponthe bell crank 79 about the stud or screw 81 is a leaf or blade spring82 which acts as' a brake affording frictional resistance to the slidingmovement of the bell crank 79. Adjacent to the picker or plectrum 78 thebell crank 79 is provided with a pin 83 which engages a slot 84 in aswinging arm 85 pivotally connected upon the cross bar 75. To obviateany metallic chatter or noise incident to the engagement of the pin 83with the arm a string 86 is tied across the slotted portion of the armto be engaged by the pin. The end of the bell crank 79 is turnedoutward, as at 87, and the picker or plectrum 78 is clamped thereto by ascrew or bolt 88 and clamp plate 89. The lateral arm of the bell crankcarries a swivel head 90 having interposed washers 91 of leather orother suitable material to prevent rattle or noise. An actuating link orrod 92 hinged to the edge of the movable side of the pneumatic andadjustably connected to the swivel head 90 servesto actuate the bellcrank 79 to cause the picker or plectrum 7 8 to engage the strings ofthe instrument. As the pneumatic or bellows is collapsed by theexhaustion of the air therefrom, as heretofore described, the pullexerted upon the connecting rod 92 oscillates the crank arm 79 downwardabout the pivotal stud 81 projecting the picker or plectrum 78 into theplane of the string. The continued movement of thepneumatic causes thebell crank 79 to slide longitudinally upon the stud or screw 81 withinthe limits of the slot 80 until the plectrum 78 has been drawn acrossthe string. Upon the reverse movement of the movable side of thepneumatic the bell crank is first oscillated upward about the stud orscrew 81 which at such time will stand adjacent to the opposite ends ofthe slot 80 and thereafter the bell crank 79 will be reciprocated tocarry the plectrum 78 over and beyond the string. The swinging arm 85serves to guide the bell crank and insure its proper path of travel. Theleaf or blade spring 82 afiords sufficient pressure or friction toprevent the reciprocatory movement of the bell crank prior to itsoscillatory movement. The path of travel of the plectrum is clearlyillustrated in the diagrammatic views Figs. 10 and 11. It will beunderstood that there is a bell crank and plectrum with its connectingrod and pneumatic for each string. In the present instance two bellcranks have been mounted upon each side of the transverse bar 75 and, asbefore stated, the pneumatics are arranged in pairs upon opposite sidesof the body. Each pneumatic is connected by a link or rod 92 with itscorresponding bell crank and plectrum. These plectrums are operated inproper sequence and in proper time order with the fingering or stoppingdevices under the control of the perforated music sheet in which theperforations 66 controlling the plectrums are located in definiterelation with the perforations 65 controlling the fingering or stoppingdevices.

After the playing of the musical composition has been completed aperforation in the sheet is brought into registry with the correspondingorifice in the tracker bar controlling a pneumatic or bellows 93 throughthe conduit 53 to effect the rewind of t e music sheet. The pneumatic 93is connected by a link or cord 94: with a pivoted arm 95 mounted upon ahinged door or fla 96 affording an inlet for air to the equa izer andmain bellows 18. This door or fla 96 is normally held closed by a spring97. The collapsing of the pneumatic 93, however, lifts the pivoted arm95 into the path of a lug or projection 98 upon the main bellows 18which, upon its succeeding operation by engaging the end of the swingingarm, forces the door or flap 96 open against the tension of the spring97 where it is engaged and held by a detent finger 99 provided with'ashoulder to engage a stud or pin in said flap or door. This admits airto the equalizer and main bellows and renders the pneumatic mechanisminoperative during the rewinding of the perforated sheet. The admissionof air permits the pneumatic 37 to expand under the influence of itsspring and thereby cause the engagement of the gear inion 35 with thegear 36 to effect the rewinding of the music sheet under the influenceof the motor inde endent of the pneumatic mechanism. As t 0 rewindingoperation is completed a stud or pin 100 located in a groove 101 in thewinding roll 11 engages the end of a pivoted spring actuated finger 102carried upon the end of a lever 103 fulcrumed at 104 upon a suitablebracket and serves to oscillate said lever against the tension of itssprin 105. This lever carries at.its rear end a downward extendinghooked extension 106 adapted to engage and lift the detent 99 when thelever is oscillated upward. The lifting of the detent 99 serves todisengage said detent sion of the from the flap or door 96 permittingsaid oor to close under the influence of its spring 97 whereupon thepump or main bellows 18 again becomes operative and the operation of themechanism is repeated. Thus the winding and rewinding of the perforatedsheet is automatically accomplished and the moven'ient'of the musicsheet is automat1- callyreversed at each limit of its travel. 10

In order tovary the intensity of the sound and produce modulation ofexpression in the playing, there is provided upon the body bar 8 oftheinstrument a flexible spring blade 107 carrying at its free end a muteor damper .108 adapted to be lifted into engagement with the under sideof the instrument head. To elevate the mute or damper 108 to operativeposition against the tenspring blade 107 there is provided a pivotedlever 109 having a pin 110 engaging beneath said spring blade and at itsopposite end provided with a connection 111 to an arm 112 carried by apneumatic 113. The construction is such that as the pneumatic 113 iscollapsed by the exhaustion of the air therefromthe lever 109 will beoscillated to. elevate the damper or mute intocontact with theinstrument head. Located adjacent to the pneumatic 113 is a pivoted arm114 having therein a notch 115 adapted to engage a pin or stud 116 inthe movable" side 'of the pneumatic to lock said pneumatic in collapsedposition and so 'maintain the mute or damper in operated condition untilreleased. To release the mute or damper there is provided a secondpneumatic 117, the movable side of which is connected by a link or cord118 with the pivoted arm 114 whereby when said second pneumatic 117 iscollapsed the arm is elevated from engagement with the pin and the firstmentioned pneumatic is permitted to expand. It is pneumatics 113 and 117are controlled by perforations in the music sheet registering withcorresponding orifices in the tracker bar.

From the above description it will be apparent that there isthusprovided a device of the character described possessing the particularfeatures of advantage before enumerated as desirable but which obviouslyis susceptible of modifications in its form, proportion, detailconstruction, or arrange ment of parts without departingfrom theprinciple involved or sacrificing any of its advantages.

While in order to comply with the statute the invention has beendescribed in language more or'less specific as to certain structuralfeatures, it is to be understood that the invention is not limited toany specific details but that the means and construction hereindescribed comprise but one mode of putting the invention into effect andthe into be understood that these vention is therefore claimed broadlyin any of its possible forms or modifications with in the scope of theappended claims.

Having thus described my invention, I claim:

1. In an automatic playing apparatus for stringed instruments, aplectrum, a bell crank on which the plectrum is carried capable of bothoscillatory and reciprocatory .movement in relation with its fulcrum,means for initially oscillating the bell crank to carry the plectruminto the plane of the string and thereafter reciprocating the bell crankto carry the plectrum across the string.

In an automatic playing apparatus for stringed instruments, a plectrum,a movable support on which the plectrum is carried capable of bothoscillatory and reciprocatory movement, and means affording yieldingresistance to the reciprocatory movement of the supportgreater than theresistance to the oscillatory movement thereof and actuating meanstherefor.

3. In an automatic playing apparatus for stringed instrun1ents, aplectrum, a movable carrier therefor, a support for the carrier, aconnection between the carrier and support in relation with whichthecarrier is capable of independent oscillatory and reciprocatorymovement, an actuator for the carrier connected thereto at a pointnormally offset in relation with the supporting connection, and meansfor operatively controlling the actuator.

4. In an automatic playing apparatus for stringed instruments, aplectrum, a movable support,- a pivotal connection about which thesupport is capable of oscillatory movement and in relation with whichthe support is slidingly adjustable, and'means for oscillating thesupport about said pivotal connection and thereafter sliding the supportin relation therewith.

5. In an automatic playing apparatus for stringed instruments, aplectrum, a support therefor having an elongated .slot therein, apivotal stud engaging in the elongated slot, and means for oscillatingthe support about the pivotal stud and thereafter sliding the supportupon said stud within the limits of the slot.

6. In an automatic playing apparatus for stringed instruments, aplectrum, a reciprocatory support therefor, a swinging arm engaged withthe support and means for reciprocating the plectrum support whileengaged by the swinging arm.

7. In an automatic playing apparatus for stringed instruments, aplectrum, a plectrum support, a swinging support for the plectrumsupport, and a fixed support therefor in relation with which the supportis slidingly movable.

8. In an automatic playing apparatus for stringed instruments, a bellcrank lever having a sliding pivotal connection,- a plectrum carried bysaid bell crank lever, and means for restraining the sliding movement ofthe bell crank lever until the pivotal movement thereof is effected.

9. In an automatic playing apparatus for stringed instruments, aplectrum, a movable support therefor, a reciprocatory link connectedwith the plectrum support, a shifting pivotal connection for the supportand means for actuating said movable support.

10. In an automatic playing apparatus for stringed instruments, atplectrum, a pivoted support therefor, means to initially oscillate thesupport and thereafter move it in a direction radially in relation withthe axis of its initial oscillatory movement.

11. In an automatic playing apparatus for stringed instruments, aplectrum, a bell crank by which the plectrum is carried, a reci rocatoryactuator connected to one arm of tlie bell crank, and a shifting pivotalconnection for the bell crank.

12. In an automatic playing apparatus for stringed instruments, aplectrum, a bell crank by which the plectrum is carried, a shiftingpivotal connection for the bell crank, an actuator therefor, and meansretarding the shiftin movement of the bell crank until said bel crankhas been initially oscillated about said pivotal connection.

13. In an automatic playing apparatus for stringed instruments, aplectrum, a bell crank by which the plectrum is carried, a shiftingpivotal connection for the bell crank, and actuating means initiallyoscillating the bell crank about its pivotal connection and thereaftershifting it in relation therewith.

14. In an automatic playing apparatus for Copies 0! this patent may beobtained for five cents each, by addressing the stringed instruments, aplectrum, a bell crank by which the plectrum is carried, a slidingpivotal connection for the crank, a swingm arm controllin the free endof the cran during its shiftin movement, and means for actuating the belcrank.

1 5. In an automatic playing apparatus for strin ed instruments, aplectrum, a bell crank by which the plectrum is carried, a slidingpivotal connection for the bell crank and a brake member retarding theshifting movement of the bell crank.

16. In an automatic playing apparatus for stringed instruments, aplectrum, a bell crank by which the plectrum is carried, a slidingpivotal connection for the bell crank, and a spring exerting pressureupon the bell crank to retard its shifting movement.

17 In an automatic playin apparatus for stringed instruments, a moculating device comprising a damper movable into engagement with the headof the instrument, means for moving the dam er to operative position, alock therefor, an means to automatically release the lock.

18. In an automatic playin apparatus for stringed instruments, a moulating device comprisin a damper movable into engagement wit the headof the instrument, a pneumatic adapted by its operation to project thedam er into en agement with the head, means or locking t e damper inoperated position, and a second pneumatic adapted upon operation torelease the damper.

In testimony whereof, I. have hereunto set my hand this 20th dav ofApril, A. D. 1915.

BENJAMIN L. CARTMELL.

Witnesses:

HARRY F. NOLAN, F. L. WALKER.

"Gommlntoner of Patents,

Washington, D. C."

